Tuning arrangement



Patented May 8, 1934 UNITED STATES PATENT OFFICE TUNING ARRANGEMENT tion of Germany Application July 18, 1930, Serial No. 468,792 In Germany August 9, 1929 7 Claims.

The present invention relates to tuning devices, and more particularly to arrangements employing variometers.

Variometers for insuring continuous variation of inductance are built in such a way that the outer coil is connected in series with the inner mobile, or rotor, coil. For coupling, for instance, an aerial or a tube, the internal coil is used with its full turns. However, in a variometer of this 10 type, the ratio of the total inductance to the degree of coupling with the antenna or tube varies as the total inductance is altered. No matter Whether the variometer is set to maximum or minimum inductance, the coupling inductance will always be the same; a fact which is apt to cause inconvenience, especially where the variometer is connected before an amplifier tube such as a screen grid tube.

Now, according to the present invention, the relationship between the coupling factor (degree) and the total inductance is maintained at a constant value by disposing one winding of the variometer between two parts of the other winding, and utilizing a part of each of the said two windings for coupling purposes. While in constructions known to the prior art, the value of the coupling inductance itself will not be altered, according to the invention the inductance of the coupler winding will be varied with variation of the total inductance in such a manner that, in the presence of maximum inductance, the coupling inductance Will also be at a maximum value, and vice versa. In this manner constant amplification is obtained inside a large frequency range, if the variometer 5 is used, for example, between two tubes as part of the coupling oscillation circuit.

The novel features which I believe to be characteristic of my invention are set forth in partic ularity in the appended claims, the invention it- 0 self, however, as to both its organization and method of operation will best be understood by reference to the following description taken in connection with the drawing in which I have indicated diagrammatically several circuit organizations whereby my invention may be carried into effect.

In the drawing,

Fig. 1 shows the form of construction known in the prior art,

Fig. 2, by way of example, shows an embodiment according to the invention,

Fig. 3 shows another form of the invention.

In Fig. 1, there is shown the conventional ar rangement of a variometer whose rotor winding or coil 1, is connected with the stationary, or stator, coil 3 by wire 2. The variometer constitutes. the inductance in an antenna oscillation circuit comprising further the variable condenser 4, the coupling means consisting of the rotor coil 1 connected between the aerial 5 and ground. It will be seen that this coupling inductance has always the same value, although the total inductance is changed upon turning the winding 1. Fig. 2 shows the variometer whose rotor winding 6 is connected between the identical parts '7 and 8 of a stator Winding. However, for coupling the aerial 9 to the screen grid tube 10, there is used here one half each of the rotor and the stator coil, with the result that upon turning the coil 6, not only the total inductance, but also the inductance of the coupler coil is altered. In the presence of maximum inductance, the coupling is the strongest; and vice versa, there is loose coupling in the presence of minimum total inductance.

The novel variometer proves particularly advantageous if, as in Fig. 3, by a convenient unicontrol mechanical connection between the variometer rotor 6 and the rotors of condenser 11 care is taken so that the impedance will preserve a constant value for a large wave range. This arrangement will be particularly useful as coupling means for amplifier tubes, ess pecially of the screen grid type, such as the tubes 20 and 21. I

While I have indicated and described several systems for carrying my invention into effect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organizations shown and described, but that many modifications in the circuit arrangements, as well as in the apparatus employed, may be made without departing from the scope of my invention as 95 set forth in the appended claims.

What I claim is:

1. In a receiver, a source of high frequency oscillations, an amplifier of high amplification, a network for coupling the source and amplifier comprising a variometer and a variable condenser, and means for simultaneously adjusting said variometer and condenser so that the impedance i RC of the networn varies in a predetermined manner over the tuning range of the receiver, said variometer including a pair of fixed inductances, and a mobile inductance connected in series with 110 the fixed inductances, said source being connected to an intermediate point of said mobile inductance.

2. In a receiver, a source of high frequency oscillations, an amplifier of high amplification, a network for coupling the source and amplifier comprising a variometer and a variable condenser, and means for simultaneously adjusting said variometer and condenser so that the impedance of the network remains constant over the tuning range of the receiver, said variometer including a pair of fixed inductances, and a mobile inductance connected in series with the fixed inductances, said source being connected to an intermediate point of said mobile inductance.

3. In a receiver, a source of high frequency oscillations, an amplifier of high amplification, a network for coupling the source and amplifier comprising a variometer and a variable condenser, and means for simultaneously adjusting said variometer and condenser so that the impedance of the network varies in a predetermined manner over the tuning range of the receiver, said variometer including a pair of fixed inductances, and a mobile inductance connected in series with the fixed inductances, said source being connected to an intermediate point of said mobile inductance, said source consisting of an antenna circuit, and said amplifier comprising a screen grid tube.

4. In a receiver, a source of high frequency oscillations, an amplifier of high amplification, a net work for coupling the source and amplifier comprising a variometer and a variable condenser, and means for simultaneously adjusting said variometer and condenser so that the impedance of the network varies in a predetermined manner over the tuning range of the receiver, said variometer including a pair of fixed inductances, and a mobile inductance connected in series with the fixed inductances, said source being connected to an intermediate point of said mobile inductance, said source and amplifier including screen grid tubes, and said intermediate point being connected to the anode of said source tube.

5. In a receiver, a source of high frequency oscillations, an amplifier of high amplification, a net work for coupling the source and amplifier comprising a variometer and a variable condenser, and means for simultaneously adjusting said variometer and condenser so that the impedance of the network remains constant over the tuning range of the receiver, said variometer including a pair of fixed inductances, and a mobile inductance connected in series with the fixed inductances, said source being connected to an intermediate point of said mobile inductance, said source and amplifier including screen grid tubes, and said intermediate point being connected to the anode of said source tube.

6. In combination with an antenna and an amplifier tube, a variable condenser connected across the input electrodes of the tube, an adjustable inductance device connected in shunt with said condenser, said device consisting of a mobile coupling coil and at least two stator coils, said antenna being connected to a point on said mobile coil, control means for simultaneously adjusting said mobile coil and adjustable element of the condenser, the said coupling coil and stator coils being so chosen that the coupling between the antenna and tube is strongest when the control means adjusts the total inductance across said condenser to a maximum.

7. In combination with an antenna and an amplifier tube, a variable condenser connected across the input electrodes of the tube, an adjustable inductance device connected in shunt with said condenser, said device consisting of a mobile coupling coil and at least two stator coils in series witla. the coupling coil, said antenna being connected to a point on said mobile coil, control means for simultaneously adjusting said mobile coil and adjustable element of the condenser, the said coupling coil and stator coils being so chosen that the coupling between the antenna and tube is strongest when the control means adjusts the total inductance across said condenser to a maximum.

PAUL MiiLLER. 

